A conventional investigation device for a sample is e.g. disclosed in U.S. Pat. No. 5,345,815. In particular, this known investigation device relates to an atomic-force microscope (AFM) which comprises a cantilever, the movement of which is picked up by means of a piezoresistive deflection sensor.
An AFM is known as an instrument in which a flexible cantilever of very small dimensions is moved relatively to a surface so as to investigate or to scan the structure of this surface. Such cantilevers typically have a sharp tip at the free (distal) end thereof. The apex of the tip projects in the direction of the sample surface. As the sample is scanned, forces (including electrostatic, magnetic, viscous, van-der-Waals and other forces) between the cantilever tip and the sample surface cause the cantilever to deflect. The deflection is measured by the integrated sensor (as e.g. the piezoresistive deflection sensor disclosed in U.S. Pat. No. 5,345,815); the output signal of this sensor is representative of the respective profile or structure of the sample and, typically, has an extraordinary resolution in the order of nanometers.
A similar type of AFM which makes use of integrated piezoresistive sensors is disclosed in the PCT Patent Application No. WO 94/298994; furtheron, an AFM device which measures the deflection of the micro-cantilever by means of an optical sensor instead of piezoresistive elements is disclosed in U.S. Pat. No. 5,388,323.
However, these known AFM devices are only capable of investigating or scanning the surface of a sample; these known AFM devices are, however, not capable of manipulating the surface. The presently known AFM devices, consequently, cannot be used for writing information onto the surface of a storage medium. On the other hand, it would be highly desirable to provide a device which both has the ability to investigate and to manipulate a sample, for example in order to provide a read/write operation for coded information on the sample.
Since an AFM is able to investigate a sample with a resolution in the order of nanometers, such an AFM device is able to read the information stored on a very small area; hence, an AFM device, in principle, has the ability to read huge amounts of information which are stored at a very high recording density. However, the investigation techniques used in these known AFM devices are not fast enough so as to be used for a read operation having a sufficiently high data transfer speed (throughput). Moreover, the power consumption of the sensor of these known devices is rather high; therefore, any attempt to speed up the data transfer rate by using a plurality of AFM tips simultaneously is drastically limited by the increasing power consumption which finally would lead to an overheating of the device.